PROJECT SUMMARY Idiopathic pulmonary fibrosis (IPF) is a progressive and irreversible interstitial lung disease with a mean life expectancy of only 3 to 5 years after diagnosis. It is one of approximately 7,000 rare diseases. The disease typically occurs in individuals between the ages of 50 and 70 years old. The abnormal activation of local resident pulmonary fibroblasts is believed to be a major factor driving the fibrotic progression in IPF. However, the molecular mechanisms leading to the fibroblast activation are not fully understood. The long-term goal of this project is to elucidate the pathogenesis of IPF and thus to advance the development of an effective pharmacological therapy. The objective of the current application is to understand how long non-coding RNAs (lncRNAs) regulate pulmonary fibroblast activation in IPF. lncRNAs are non-protein-coding RNAs with a size of > 200 nucleotides that have been increasingly recognized for their importance in regulating various biological processes. Although small non-coding RNAs, such as microRNAs, have been extensively studied in IPF, very little is known regarding the roles of lncRNAs in the pathogenesis of pulmonary diseases, such as IPF. Through the analyses of RNA_seq datasets, we have identified human fetal-lethal non-coding developmental regulatory RNA (FENDRR) as an lncRNA that is down-regulated in the fibrotic lungs of patients with IPF. Our preliminary studies have shown that TGF?1 and hypoxia reduce FENDRR expression in pulmonary fibroblasts and that the overexpression of FENDRR inhibits fibroblast activation. We have also demonstrated that FENDRR reduces cellular iron content, and that iron depletion decreases pro-fibrotic miR- 214 expression. In addition, we have shown that FENDRR is a competing endogenous RNA (ceRNA) that functions as a sponge for miR-214. Finally, we have provided evidence that adenovirus-mediated gene transfer of FENDRR into mouse lungs attenuates bleomycin-induced pulmonary fibrosis in preventive and therapeutic modes. The central hypothesis of this project is that the down-regulation of FENDRR in IPF contributes to pulmonary fibrosis by promoting fibroblast activation via increased expression and activity of pro-fibrotic miR-214 due to iron overload and a reduced competition between FENDRR and miR-214, respectively. Aim I will delineate the transcriptional regulation of FENDRR by the TGF? and hypoxia signaling pathways. Aim II will define the functional roles and molecular mechanisms of FENDRR in fibroblast activation. Aim III will determine the therapeutic efficacy and mechanisms of action of Fendrr in pre-clinical pulmonary fibrosis mouse models. The proposed studies will define novel mechanisms involved in the pathogenesis of IPF.